The babies were lying on their backs on the rug, singing as they watched Lauren. Their eyes were almost completely transformed into a bright shade of green, so different from the blue her real boys had. They were goading her, with this song, with their staring. She gritted her teeth and did not react. With exaggerated nonchalance, she leaned forward to pick up a plastic cup of water and their twin gazes followed her, the movements of their heads synchronised, like all their movements when they weren’t pretending to be Morgan and Riley. Staring back at them, she said nothing, pressed her lips together in a thin line. She wanted to plug her ears so she couldn’t hear the terrible, gurgling, high-pitched hum of it. The tune was the same as the one their mother sang in the hospital when the boys were only hours old, before the swap, before the nightmare started. They sang it wordlessly, yet the tune lit up the words in her mind, as they probably knew it would, and she couldn’t help but think of the story it told, two poor illegitimate babes, bloody and abandoned. “The Cruel Mother”, that was the name of it. The choice of song seemed accusatory. In it, a mother threw her babies away. I’m not abandoning you, she silently told the creatures, because I’m not your mother. She abandoned you. I’m just putting things right. She did it all, blame her. Sing the fucking song to her.

In the past three days she’d used up all her fear, and what was left was a kind of ground-up weariness and a whole lot of disgust. Lauren could have alerted the hospital to what the twins were doing. It had been in front of the camera, after all—she could have made them watch the footage and that in itself would have proved that she was sane. Or she could have suggested that they question her fellow patient Felicity, who’d heard them singing, who’d first told Lauren the names they called each other when they thought no one else was listening. But nothing had convinced Lauren that, even with the evidence in front of them, anyone would see the truth. It was too risky to try it now—suppose the CCTV hadn’t worked, and they dismissed her story as crazed ranting? Felicity had psychosis: she wasn’t a reliable witness. Best to stay with the plan, now that there was only this small, crucial hurdle to get past. No one was going to help her. Certainly not Patrick—he couldn’t even begin to understand it. And not even Jo Harper, who’d seen the creatures unmask themselves, and still walked away.

The door opened and the twins immediately stopped humming and started pretending to be Morgan and Riley. Doctor Summer stepped cautiously around the two small bodies and sat down opposite Lauren, smiling, placing a clipboard on the side table.